Компилятор Фортрана

Собирающаяся версия кода

!-----------------------------------------------------------
      program MATRIX
!-----------------------------------------------------------

      implicit none
      call Main(10)
      print *, 'Well done.'
      read *

!-----------------------------------------------------------
      contains
!-----------------------------------------------------------

      subroutine Main(dim)
      integer i, j, dim
      real a(dim, dim), r(dim), x(dim), r2(dim), r3(dim)
      open(unit=2, access='sequential', status='old', file='array.dat')
      do i=1,dim
      read(2, 100) (a(i, j), j=1,dim)
      end do
      read(2, 100) (r(i), i=1,dim)
100   format(F7.2)
      call ThreeDiagonalMatrixSolve(dim, a, r, x)
      call Multiplication(dim, a, x, r2)
      call Subtraction(dim, r, r2, r3)
      open(unit=3, access='sequential', file='output.dat')
      write(3, 200) (x(i), i=1,dim)
      write(3, 200) (r3(i), i=1,dim)
200   format((F7.2))
      end subroutine Main

      subroutine ThreeDiagonalMatrixSolve(dim, a, r, x)
      integer dim, i, j
      real a(dim, dim), r(dim), x(dim), c(dim), d(dim), b(dim)
      real l(dim), s(dim)
      do i=1,dim
      if (i.eq.1) then
      b(i) = 0
      else
      b(i) = a(i, i-1)
      end if
      c(i) = a(i, i)
      if (i.eq.dim) then
      d(i) = 0;
      else
      d(i) = a(i, i+1)
      end if
      end do
      do i=1,dim
      if (i.eq.1) then
      l(i) = r(i)/c(i)
      s(i) = - d(i)/c(i)
      else
      l(i) = (r(i) - b(i)*l(i-1))/(c(i) + b(i)*s(i-1))
      s(i) = - d(i)/(c(i) + b(i)*s(i-1))
      end if
      end do
      do i=1,dim
      j = dim - i + 1
      if (j.eq.dim) then
      x(j) = l(j)
      else
      x(j) = s(j)*x(j+1) + l(j)
      end if
      end do
      return
      end subroutine ThreeDiagonalMatrixSolve

      subroutine Multiplication(dim, a, x, r)
      integer i, j, dim
      real a(dim, dim),x(dim),r(dim)
      do i=1,dim
      r(i) = 0
      do j=1,dim
      r(i) = r(i) + a(i,j) * x(j)
      end do
      end do
      return
      end subroutine Multiplication

      subroutine Subtraction(dim, a, b, c)
      integer i, dim
      real a(dim), b(dim), c(dim)
      do i=1,dim
      c(i) = a(i) - b(i)
      end do
      return
      end subroutine Subtraction

!-----------------------------------------------------------
      end program MATRIX
!-----------------------------------------------------------

Разница в форматировании в метках и в FORMAT
С той либой собирать не пробовал... Есть другие не хуже...
А в некоторых случаях даже лучше...

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